With the recent demand for small-sized, large-capacity devices in ceramic capacitors, monolithic ceramic capacitors have become increasingly popular. Monolithic ceramic capacitors are produced by alternately laminating inner electrode layers and dielectric ceramic layers followed by firing the resulting laminate. For the dielectric ceramic layers are used ceramic capacitor materials having a high dielectric constant. The monolithic ceramic capacitors thus produced have a large capacitance.
Heretofore, barium titanate-type materials have been widely used as such high dielectric ceramic capacitor materials. However, those materials must be fired at high temperatures of not lower than 1300.degree. C. Therefore, when they are used in producing monolithic ceramic capacitors, expensive noble metals such as platinum and palladium must be used to form the inner electrodes in the capacitors.
On the other hand, some recent reports have proposed the use of lead-containing composite perovskite compounds which can be fired at low temperatures and have a high dielectric constant as the materials for monolithic ceramic capacitors. For example, it is reported in JP-B-01-46471 that a two-component composition comprising lead nickel niobate Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3 and lead titanate PbTiO.sub.3 has an extremely high dielectric constant.
However, the firing temperature for the conventional barium titanate-type materials is not less than 1300.degree. C. and that for the conventional lead-containing composite perovskite compounds is about 1100.degree. C. Therefore, all those conventional materials are problematic in that they could not be fired together with inexpensive silver and silver alloys. In particular, where the conventional barium titanate-type materials and lead-containing composite perovskite compounds are used to produce monolithic ceramic capacitors, inexpensive silver or silver alloys could not be employed to form the inner electrodes for those capacitors, making it is impossible to produce monolithic ceramic capacitors at a low production cost.